Reducing risk is a major objective of the concept demonstration phase of the JSF project. To that end, the programme office is funding technology maturation (TechMat) projects, the results of which are being shared by the two design teams.
Among the largest of these, exceeding $100 million, is the Joint/Integrated Systems Technology (J/IST) demonstration. There are two major elements to this programme: ground and flight tests of "power-by-wire" electric actuation to replace hydraulic flight controls; and ground tests of a thermal and energy management module (T/EMM) that integrates the environmental control system and auxiliary and emergency power units. Together, they allow the accessory gearbox and hydraulic system to be eliminated to save weight, space and cost.
In December 1995, when the programme was started, integrated systems technology was considered high risk. Now, past the halfway mark in the 48-month effort, risk has been reduced to moderate, says the JSF programme office. The aim is to achieve low risk by July 2000, in time for entry into the engineering and manufacturing development programme.
The J/IST programme is split 60:40 between Boeing and Lockheed Martin, but the results are shared equally. The schedule calls for a sequence of increasingly ambitious demonstrations, beginning with virtual simulations and culminating in flight tests of a power-by-wire F-16 and ground tests of the T/EMM integrated with Pratt & Whitney's F119 JSF engine.
The T/EMM, designed by AlliedSignal, is a small gas turbine that drives a switched-reluctance starter/generator to provide electrical power. The engine is started electrically, and the T/EMM combustor then switches from burning outside air to using engine bleed air to drive the environmental control system.
So far, says the programme office, installation, maintenance and control of the T/EMM in all 10 of its modes have been demonstrated in simulations. In March, rig testing validated operation of the combustor for a turbomachinery core demonstration planned for mid-June.
The integrated turbomachinery demonstration is planned for January next year, leading to a system demonstration in September. The most complex of the J/IST tasks, the integrated T/EMM-engine demonstration, is scheduled for March 2000 and will involve everything from engine starting to providing power for an "all-electric" aircraft.
Lockheed Martin, meanwhile, is replacing the hydraulic flight controls in an F-16 with a 270V DC power-by-wire system and four months of ground tests are scheduled to begin in August. The system includes a 200kW dual-channel switched-reluctance generator driving five identical electro-hydraulic actuators on the flight controls. A first flight is scheduled for January next year.
The programme office says that the J/IST demonstration will answer "about 80% of the questions". The other 20% is unique to each team's application of the technology, it says, and the maturation effort will produce "-design tools to scale and size real hardware and to predict cost, weight and performance".
Source: Flight International
